ADJUSTABLE COOLANT PUMP

Abstract

The invention is based on the task of developing an adjustable coolant pump driven by the engine, which pump does not require any outside energy for pressure and/or volume stream regulation, guarantees great failure safety, and is supposed to guarantee optimal warm-up of engines having great engine outputs relative to the displacement, which require coolant pumps having a very large design. The adjustable coolant pump according to the invention, having an impeller disposed in torque-proof manner on a pump shaft, having a ring piston spring-loaded by a return spring, axially guided in a pump housing, on which piston a control slide valve disposed in the pump interior is rigidly attached, and which is characterized in that the ring piston and a filter sleeve provided with laser bores, together with other components, form a spring pressure space in the form of a ring cylinder in the interior of the coolant pump, which chamber is connected with a pressure chamber disposed on the pump shaft side, in such a manner that the valve piston of the pilot valve closes off a shaft bore disposed centrally in the pump shaft, which bore opens into the pressure chamber by way of transverse bores disposed in the pump shaft.

Description

[0001] The invention relates to an adjustable coolant pump, particularly for use in internal combustion engines.

[0002] Within the scope of the optimization of internal combustion engines, these have a tendency toward constantly greater engine outputs, while the displacement remains the same or often becomes smaller.

[0003] It is compulsory that the cooling output of the coolant pumps must be adapted to these greater engine outputs, so that in the case of engines having an increasing engine output, the related coolant pump must already summon up a correspondingly great conveying output in the lower speed of rotation range, and must be dimensioned to he correspondingly large, and this necessarily requires an increased space requirement in the engine compartment. However, in order to not have the conveying pressure generated by the coolant pump increase so greatly with an increasing speed of rotation that as a consequence of a pressure buildup that results in the coolant system of the internal combustion engine, modules such as heat exchangers, for example, are destroyed, the most varied pressure regulation functions are used. However, their use in turn requires a further demand for space in the engine compartment, and furthermore often requires auxiliary energies for activation, which energies roust be made available by way of supply lines, which require an even greater demand for space.

[0004] Thus, in the state of the art, overpressure protection is implemented by way of bypass lines, for example, wherein such solutions necessarily result in great energy losses.

[0005] A further possibility for implementing a pressure regulation function was previously described in DE 881 306 B. This is a centrifugal pump having a hydraulically activated control slide valve. The conveying pressure of the pump is used as the activation pressure. A spring causes the slide valve to be closed in the normal position/starting position.

[0006] In this solution, the displacement piston has a conveying pressure applied to it on both sides. When needed, the spring space can be relieved of pressure by way of an external valve, thereby initiating an adjustment of the control slide valve in the "open" direction.

[0007] Because of the required inner and outer guide of the slide valve, this embodiment requires very cost-intensive, complex production, and furthermore an external control valve as well as externally conducted drain lines, so that this design requires a great demand for space/construction space. A further significant disadvantage of the design previously described in DE 881 306 B consists in that this solution cannot guarantee the failure safety (fail-safe) that is absolutely required for coolant pumps, because the conveying volume stream is completely closed off if the regulation device fails. Furthermore, in this design, the displacement piston sealing surfaces are also not protected against particles entrained by the conveying medium, on the one hand, and on the other hand, the shaft seal is subject to the stress of the full conveying pressure, so that not only the useful lifetime but also the reliability of the pump is greatly restricted.

[0008] Furthermore, the applicant presented a coolant pump having a pressure regulation function by means of a valve slide valve, which has proven itself in practice in the meantime, in EP 1657446 A2, in which pump this valve slide valve is adjusted by a central working piston disposed around the pump shaft, against which piston a return spring that is disposed around the pump shaft and adjusts/resets the valve slide valve into the "fully open" starting position rests.

[0009] In this design, the impeller is furthermore mounted on the shaft in axially displaceable but torque-proof manner. The conveying pressure acts between the pressure slant in the housing and the open impeller, and displaces the impeller counter to the spring force of a plate spring that lies against the rear side of the impeller when a preset value has been reached. The conveying pressure of the pump decreases as a result of the sealing gap relative to the pressure slant becoming larger during this axial displacement of the impeller. A prerequisite for this is that a space (i.e. the spring space) having a lower pressure level as compared with the conveying pressure is present on the rear side of the impeller.

[0010] However, in this solution, too, the coolant pump requires a relatively large construction space as a consequence of the control unit that can be controlled externally with outside energy, the magnetic coil.

[0011] The setting element/spring element that "makes do" without outside energy in this solution, and has a pressure regulation function, is a plate spring used due to limitations of the construction space, which spring is very greatly restricted in terms of its force/lift ratio, so that the opening pressure can be adjusted only very imprecisely with this solution.

[0012] A further solution of a design of a coolant pump having a pressure regulation function, here once again with a control slide valve, which design has also proven itself in practice in the meantime, was presented by the applicant in DE 10 2008 026 218 B4 and also in WO 2009/143832 A2. In this solution, the control slide valve is disposed on an a spring-loaded, axially displaceable ring piston, wherein the control pressure for activation of the control slide valve is generated by an axial piston pump that lies against the rear wall of the pump wheel, which wall is specifically configured as a slanted disk for this purpose, and adjusted by means of a solenoid valve disposed in the pump housing.

[0013] As the result of the use of the axial piston pump, this solution once again requires an increased demand for space in the engine compartment, as well as, furthermore, also in connection with the use of the solenoid valve, once again outside energy with the related supply lines.

[0014] In the prior art, the applicant furthermore presented a further solution that has also proven itself in practice in the meantime, in DE 10 2008 022 354 A1, which also allows active control of the conveying volume stream by means of a valve slide valve spring-loaded by a return spring, having a rear wall and an outer cylinder that is disposed on this rear wall and variably covers the outflow region of the impeller.

[0015] In the solution according to DE 10 2008 022 354 A1, the required hydraulic pressure that brings about the displacement of the spring-loaded valve slide valve, counter to the spring force of the return spring, is generated and, at the same time, adjusted by means of an electromagnetically activated, special axial pump disposed on the outside of the pump housing.

[0016] A further solution is known from DE 10 2012 207 387 A1, by means of which a valve slide valve spring-loaded by a return spring, once again having a rear wall and an outer cylinder disposed on this rear wall and variable covering the outflow region of the impeller, can be hydraulically adjusted by means of a 3/2-way valve, wherein the hydraulic pressure required for adjustment of the slide valve is generated by a "second" impeller disposed on the pump shaft of the impeller, of a further secondary pump integrated into the housing.

[0017] The invention is therefore based on the task of developing an infinitely adjustable coolant pump (having a control slide valve), driven by way of an drive wheel, which avoids all the disadvantages of the state of the art mentioned above, furthermore demonstrates clear energy advantages as compared with constant pumps having an overpressure valve, particularly does not require any outside energy (such as hydraulics, vacuum, electrical energy) for pressure or volume stream regulation, guarantees great failure safety (fail-safe), and is supposed to guarantee optimal heating of engines having great engine outputs with reference to the displacement, which require coolant pumps having a large design, and is supposed to influence the engine temperature during long-term operation, in infinite manner, in highly dynamic manner, and very reliably, over very long periods of use, in very precise manner, and, in this regard, at the same time, is supposed to have a minimal construction size that optimally utilizes the construction space present in the engine compartment, wherein the coolant pump to be developed is furthermore supposed to be able to be produced in simple and cost-advantageous manner, in terms of production and installation technology, and is supposed to constantly guarantee great operational safety and great reliability over the entire useful lifetime.

[0018] According to the invention, this task is accomplished by an adjustable coolant pump driven by way of a drive wheel, for internal combustion engines, in accordance with the characteristics of the independent claim of the invention.

[0019] Advantageous embodiments, details, and characteristics of the invention are evident from the dependent claims as well as from the following description of the solution according to the invention, in connection with four representations of the solution according to the invention.

[0020] The figures show:

[0021] FIG. 1: the adjustable coolant pump according to the invention, disposed on an engine housing 37, in a side view, in section;

[0022] FIG. 2: the pump shaft 4 with the pilot valve 20 in a spatial exploded representation;

[0023] FIG. 3: the detail Z from FIG. 1 with a schematic representation of the "control streams" during the "opening phase" of the control slide valve 12;

[0024] FIG. 4: the detail Z from FIG. 1 with a schematic representation of the "control streams" during the "closing phase" of the control slide valve 12.

[0025] FIG. 1 shows the adjustable coolant pump according to the invention, disposed on an engine housing 37, having a pump housing 1, a pump shaft 4 mounted on the pump housing 1 in a pump bearing 2, driven by a drive wheel 3, here in the design of a pulley 40, having an impeller 5 disposed in torque-proof manner on a free, flow-side end of this pump shaft 4, and having a ring piston 7 spring-loaded by a return spring 6, axially guided in the pump housing 1, on which piston the rear wall 8 of a control slide valve 12 disposed in the pump interior 9 and having an outer cylinder 11 that variably covers the outflow region 10 of the impeller 5 is rigidly attached, wherein a shaft seal 14 is disposed in a seal accommodation 13, between the pump shaft 4 and the pump housing 1, and furthermore, pump mandrels 15 formed by the pump housing 1 or disposed on the pump housing 1 are disposed in the pump interior 9, on which mandrels a wall disk 16 positioned in a fixed position in the pump interior 9, between the impeller 5 and the rear wall 8 of the control slide valve 12, is disposed.

[0026] It is essential to the invention that a slide valve guide 17 for the ring piston 7 spring-loaded by the return spring 6 is disposed on the pump housing 1, which guide guides the ring piston 7 on the outer mantle and, at the same time, is furthermore at a free distance from the pump shaft 4 with its inner mantle.

[0027] It is furthermore characteristic that the slide valve guide 17 lies against the wall disk 16 with its free, flow-side end, so that the components that are adjacent to one another, i.e. the slide valve guide 17, the wall disk 16, a sealing disk 33 disposed on the inner circumference of the disk, spaced apart from the pump shaft 4 by a throttle gap, radially movable on the wall disk 16, the pump shaft 4, and the shaft seal 14, jointly enclose/form a pressure chamber 18 in the form of a ring cylinder.

[0028] The sealing disk 33, disposed in the wall disk 16 in radially movable manner, the inside diameter of which has only little play (tight running seat) relative to the outside diameter of the pump shaft 4, represents a throttle gap that permits only slight leakages into the pressure chamber 18.

[0029] In this regard, it is guaranteed by the placement of the shaft seal ring 14 in the pressure chamber 18, according to the invention, in connection with the entire pump structure according to the invention, that the shaft seal ring 14 is protected against impermissibly high pressures under all operating conditions, and thereby a long useful lifetime of the shaft seal ring 14 is guaranteed, at great reliability.

[0030] It is also essential, in this regard, that one/multiple passage bore(s) 19 is/are disposed in the slide valve guide 17, at a distance from the wall disk 16.

[0031] It is furthermore essential to the invention that a pilot valve 20 consisting of a setting screw 22 provided with a central outlet bore 21, a valve spring 23, and a valve piston 24 are disposed in a valve seat bore at the impeller-side free end of the pump shaft 4, in such a manner that the valve piston 24 closes off a shaft bore 25 that opens into the valve seat bore, disposed centrally in the pump shaft 4, in the closed state of the pilot valve 20, which shaft bore opens into the pressure chamber 18 by way of one/multiple transverse bore(s) 26 disposed in the pump shaft 4. To clarify the structure, the pilot valve 20, the pump shaft 4 having the pilot shaft 20 are shown in a spatial exploded representation in FIG. 2.

[0032] It is also characteristic, however, that the return spring 6, which lies against the ring piston 7 with one spring end, lies against the spring contact 27 of a filter sleeve 29 provided with laser bores 28 with its other spring end, and presses the sleeve against the wall disk 16 in this regard, forming a seal.

[0033] The laser bores 28 prevent the entry of any dirt load and thereby increase the reliability of the control apparatus according to the invention. At the same time, the laser bores 28 in the arrangement according to the invention serve as an inflow aperture and guarantee that the amount of liquid flowing in is not more than can drain away by way of the pilot valve 20.

[0034] In this regard, however, it is also essential to the invention that a filter piston slide valve 30 is rigidly disposed on the ring piston 7, which valve slides along the outside circumference of the filter sleeve 29 when the ring piston 7 is displaced, and thereby frees the filter sleeve 29 of any dirt load, i.e. cleans the laser bores 28/(filter bores) disposed in the filter sleeve 29 of the dirt particle accumulations in their inflow region, and thereby guarantees great reliability, even under extreme conditions of use. It is furthermore characteristic that the ring piston 7, together with the filter piston slide valve 30, the filter sleeve 29, the wall disk 16, and the slide valve guide 17 enclose a spring pressure space 31 in the form of a ring cylinder.

[0035] It is also essential that a control slide valve seal 32 is disposed on the outside circumference of the wall disk 16, i.e. toward the outer cylinder 11, and the sealing disk 33 is disposed on the inside circumference of the wall disk 16, and as a result, an impeller rear side space 34 disposed in the pump interior 9, between the pump shaft 4, the rear wall of the impeller 5, the wall disk 16, and the outer cylinder 11 is separated, on the pressure side, from a control slide valve interior 36 disposed between the rear wall 8, the filter sleeve 29, the wall disk 16, and the outer cylinder 11, wherein the working pressure that is built up in the spiral channel 39 is constantly applied in the control slide valve interior 36, in that mandrel passages 35 are disposed in the rear wall 8.

[0036] Now that the solution according to the invention has been explained, in terms of its structure, using FIGS. 1 and 2, the method of functioning/method of action of the coolant pump according to the invention, the structure of which has been explained, will now be discussed using FIGS. 3 and 4.

[0037] FIG. 3 shows the detail Z from FIG. 1 with a schematic representation of the "control streams" during the "opening phase" of the control slide valve 12. In this movement direction of the control slide valve 12, referred to as the "opening phase" (represented in FIG. 3 with a directional arrow R on the control slide valve 12), the control slide valve 12 moves in the direction of the pulley 40 and, in this regard, opens the outflow region 10 of the impeller 5 with its outer cylinder 11.

[0038] With an increasing speed of rotation of the pump shaft 4, the speed of rotation of the impeller 5 increases, and thereby the working pressure increases, i.e. the pressure in the spiral channel 39. This working pressure builds up in the entire interior of the coolant pump according to the invention, which interior is not sealed off in any special way.

[0039] In this regard, a lower pressure, as compared with the working pressure, is applied to the impeller rear side space 34 (which is sealed off relative to the control slide valve interior 36) and to the spring pressure space 31 (which is connected with the control slide valve interior 36 by way of the filter sleeve 29, provided with laser bores, which acts as a throttle).

[0040] Because the spring pressure space 31 is connected with the pressure chamber 18 by way of the passage bores 19, and this chamber is connected with the shaft bore 25 by way of the transverse bores 26, the same pressure is applied to the valve piston 24 of the pilot valve 20 as directly behind the filter sleeve 29 in the spring pressure space 31; this pressure will be referred to as the control pressure in the further explanations. This control pressure engages at the ring surface of the ring piston 7 to which this pressure is applied. The resulting pressure force will be referred to as control pressure force hereinafter. The spring force of the return spring 6, directed in the same direction as this control pressure force, furthermore also engages on the ring piston 7.

[0041] In total, the control pressure force and the spring force form an opening force that engages on the ring piston 7. This opening force strives to displace the control slide valve 12, which is rigidly connected with the ring piston 7, into the end position on the drive side.

[0042] A closing pressure force directed counter to the opening force engages at the control slide valve 12, which force proceeds from the surface to which working pressure is applied at the ring piston 7. In the calculation of the closing pressure force, the surfaces of the ring piston 7 (and also of the control slide valve 12), to which the working pressure is applied in "opposite" manner, and the effects of which cancel one another out as activations at the control slide valve 12, are left out of account.

[0043] FIG. 4 shows the detail Z from FIG. 1 with a schematic representation of the control streams of the "closing phase" of the control slide valve 12. In this movement direction of the control slide valve 12, referred to as the "closing phase" (represented in FIG. 4 with a directional arrow R on the control slide valve 12), the control slide valve 12 moves in the direction of the impeller 5 and, in this regard, closes off the outflow region 10 of the impeller 5 with its outer cylinder 11.

[0044] After the pressure has increased to such a point, in connection with the working play of the ring piston 7 (with the control slide valve 12 disposed on it) described in connection with FIG. 3, that the control slide valve 12 makes contact in its end position on the drive side, the working pressure necessarily continues to increase with an increasing speed of rotation of the pump shaft 4 (i.e. with an increasing the speed of rotation of the impeller 5), and could endanger the modules in the cooling system of the internal combustion engine without "regulation of the working pressure."

[0045] However, since the control pressure preset by way of the "throttle," the filter sleeve 29, continues to also increase as a result of the arrangement according to the invention, with an increasing working pressure, and this pressure, as has already been explained, is applied directly to the valve piston 24 of the pilot valve 20, the pilot valve 20 can be pre-adjusted when a maximal permissible working pressure is reached, in such a manner that the valve then opens, and, in this regard, the cooling medium situated in the pressure chamber 18, is emptied into the suction channel 38, as shown in FIG. 4. In this regard, the laser bores 28 in the "inflow aperture," the filter sleeve 29, are designed/dimensioned, in terms of number and size, in such a manner that the amount of coolant that flows In through the filter sleeve 2S is not greater than can drain away by way of the pilot valve 20.

[0046] In this regard, pressure relief takes place in the pressure chamber 18, as well as in the spring pressure space 31 connected with the pressure chamber 18 by way of the passage bore 19, thereby the control pressure force decreases, and if the spring force remains constant, the opening force therefore decreases below the value of the closing pressure force that is dependent on the respective working pressure, so that the closing pressure force, which is greater relative to the opening force, now brings about displacement of the ring piston 7 (with the control slide valve 12 disposed on it) in the direction of the impeller 5. In this regard, the control slide valve 12 closes the outflow region 10 of the impeller 5 off with its outer cylinder 11, and the working pressure drops.

[0047] When the engine is shut off, the working pressure also drops to "zero," and thereby both the opening pressure and the closing pressure drop to "zero."

[0048] At this force ratio, only the spring force of the return spring 6 engages on the ring piston 7 any longer, and displaces the ring piston 7 (with the control slide valve 12 disposed on it) in the end position on the drive side/pulley side, i.e. into the "fully" open position.

[0049] Optimal adjustment of the working pressure, which avoids the disadvantages of the state of the art, has clear energy advantages, does not require any outside energy (such as hydraulics, vacuum, electrical energy) for pressure or volume stream control, guarantees great failure safety (fail-safe), and guarantees optimal warm-up of engines at great engine outputs, with reference to the displacement, which outputs require coolant pumps having very large designs, and with which the engine temperature can be adjusted very precisely, even after the engine has warmed up, during long-term operation, in infinite manner, in highly dynamic manner, and very reliably, over very long periods of use, and which simultaneously has a minimal construction size that optimally utilizes the construction space present in the engine compartment, furthermore can be produced in simple manner, in terms of production and installation technology, and in cost-advantageous manner, and which constantly guarantees great operational safety and great reliability over the entire useful lifetime, results from the interplay of the effects of the arrangement according to the invention, as explained.

REFERENCE SYMBOL LIST

[0050] 1 pump housing

[0051] 2 pump bearing

[0052] 3 drive wheel

[0053] 4 pump shaft

[0054] 5 impeller

[0055] 6 return spring

[0056] 7 ring piston

[0057] 8 rear wall

[0058] 9 pump interior

[0059] 10 outflow region

[0060] 11 outer cylinder

[0061] 12 control slide valve

[0062] 13 seal accommodation

[0063] 14 shaft seal

[0064] 15 pump mandrel

[0065] 16 wall disk

[0066] 17 slide valve guide

[0067] 18 pressure chamber

[0068] 19 passage bore

[0069] 20 pilot valve

[0070] 21 outlet bore

[0071] 22 setting screw

[0072] 23 valve spring

[0073] 24 valve piston

[0074] 25 shaft bore

[0075] 26 transverse bore

[0076] 27 spring contact

[0077] 28 laser bore

[0078] 29 filter sleeve

[0079] 30 filter piston slide valve

[0080] 31 spring pressure space

[0081] 32 control slide valve seal

[0082] 33 sealing disk

[0083] 34 impeller rear side space

[0084] 35 mandrel passage

[0085] 36 control slide valve interior

[0086] 37 engine housing

[0087] 38 suction channel

[0088] 39 spiral channel

[0089] 40 pulley

[0090] R directional arrow

Claims

1: Adjustable coolant pump having a pump housing (1), a pump shaft (4) mounted in/on the pump housing (1) in a pump bearing (2), driven by a drive wheel (3), an impeller (5) disposed in torque-proof manner on a free, flow-side end of this pump shaft (4), having a ring piston (7) spring-loaded by a return spring (6), axially guided in the pump housing (1), on which piston the rear wall (8) of a control slide valve (12) disposed in the pump interior (9) and having an outer cylinder (11) that variably covers the outflow region (10) of the impeller (5) is rigidly attached, wherein a shaft seal (14) is disposed in a seal accommodation (13), between the pump shaft (4) and the pump housing (1), and furthermore, pump mandrels (15) by the pump housing (1) or disposed on the pump housing (1) are disposed in the pump interior (9), on which mandrels a wall disk (16) positioned in a fixed position in the pump interior (9), between the impeller (5) and the rear wall (8) of the control slide valve (12), is disposed, wherein a slide valve guide (17) for the ring piston (7) spring-loaded by the return spring (6) is disposed on the pump housing (1), which guide guides the ring piston (7) on the outer mantle and is at a free distance from the pump shaft (4) with its inner mantle, wherein the slide valve guide (17) lies against the wall disk (16) with its free, flow-side end, so that the components that are adjacent to one another, i.e. the slide valve guide (17), the wall disk (16), a sealing disk (33) disposed on the inner circumference of the disk, spaced apart from the pump shaft (4) by a throttle gap, radially movable on the wall disk (16), the pump shaft (4), and the shaft seal (14) jointly enclose/form a pressure chamber (18) in the form of a ring cylinder, and wherein one/multiple passage bore(s) (19) is/are disposed in the slide valve guide (17), at a distance from the wall disk (16), wherein, a pilot valve (20) comprising a setting screw (22) provided with one/multiple outlet bore(s) (21), a valve spring (23), and a valve piston (24) are disposed in a valve seat bore at the impeller-side free end of the pump shaft (4), in such a manner that the valve piston (24) closes off a shaft bore (25) that is disposed centrally in the pump shaft (4) and, in the closed, state of the pilot valve (20), opens into the pressure chamber (18) by way of one/multiple transverse bore(s) (26) disposed in the pump shaft, wherein the return spring (6), which lies against the ring piston (7) with one spring end, lies against the spring contact (27) of a filter sleeve (29) provided with laser bores (28) with its other spring end, and presses the sleeve against the wall disk (16) in this regard, forming a seal, wherein a filter piston slide valve (30) is rigidly disposed on the ring piston (7), which valve slides along the outside circumference of the filter sleeve (29) when the ring piston (7) is displaced, and wherein the ring piston (7), together with the filter piston slide valve (30), the filter sleeve (29), the wall disk (16), and the slide valve guide (17) enclose a spring pressure space (31) in the form of a ring cylinder, and wherein a control slide valve seal (32) is disposed on the outside circumference of the wall disk (16), i.e. toward the outer cylinder (11), and the sealing disk (33) is disposed on the inside circumference of the wall disk (16), and as a result, an impeller rear side space (34) disposed in the pump interior (9), between the pump shaft (4), the rear wall of the impeller (5), the wall disk (16), and the outer cylinder (11) is separated, on the pressure side, from a control slide valve interior (36) disposed between the rear wall (8), the filter sleeve (29), the wall disk (16), and the outer cylinder (11), wherein the working pressure that is built up in the spiral channel (39) is constantly applied in the control slide valve interior (36), in that mandrel passages (35) are disposed in the rear wall (8).

2: Adjustable coolant pump according to claim 1, wherein the pump housing (1) is flanged onto an engine housing (37), in which the suction channel (38) and the spiral channel (39) are integrated.

3: Adjustable coolant pump according to claim 1, wherein the drive wheel (3) is a pulley (40).